Fish emulsion is known as a fast-action plant starter for the cold, early months of the year. It is also one of the oldest commercial organic plant foods. It is made from oil and liquid by-products of an inedible fish called a menhaden. Oils are extracted to prevent rancidity, and phosphoric or sulphuric acid is added to stabilize the liquid. These also increase the nutrient content. A Colorado State University report on organic fertilizers rates fish emulsion’s N-P-K analysis as 5-2-2. Many home gardeners seek organic alternatives to fish emulsion because of its odor.
Fish meal organic plant food is made from ground, heat-dried solid fish parts. It is high in nitrogen and phosphorus, with an N-P-K of 10-6-2. Fish meal has a release time of one to four months, providing a steady contribution to microbial activity in the soil. Fish waste products are also high in other nutrients essential for healthy plant growth. It does not have the odor typical to fish emulsion.
Compost tea can be easily made by putting a scoopful of mature compost in a bucket, filling it with water and allowing it to steep overnight. Mature compost contains billions of tiny living organisms that create the necessary nutrients for plant health. They reproduce quickly in the water, especially when it is placed in the sun and stirred to introduce oxygen. Compost tea can be sprayed on plants or used to irrigate. As a foliar spray, the nutrients are absorbed quickly by leaves.
Worm compost is made into a tea and used in the same way compost tea is used. Many local recycling workshops teach worm composting and make worm bins available at a reasonable fee. Worm compost is a fine, dark brown or black material that has no odor. It is five times higher in nitrogen than normal garden soil.Compost worms are the red wiggler variety which feed entirely from decaying plant materials and kitchen food scraps.
Bat guano is very high in nitrogen, with a typical N-P-K of 10-3-1.Some bat guano is harvested for its high phosphorus content and sold as N-P-K 3-10-1. It is harvested from bat caves and dried into powdered form. Bat guano can also be made into liquid and used as a foliar spray or to irrigate plants. Bat guano is a popular ingredient in many organic fertilizers and is listed as an allowed material by the Organic Materials Review Institute.